Acrylonitrile Detection Using Biased Electrochemical Sensor

Abstract

The present application relates to acrylonitrile detection using a biased electrochemical sensor. The present invention provides an electrochemical acrylonitrile sensor, which includes a housing, an electrolyte disposed in the housing, and a plurality of electrodes in contact with the electrolyte in the housing. The plurality of electrodes include a working electrode and a counter electrode. The electrode includes a catalytic material, which may include gold. A potential is applied between the counter electrode and the working electrode.

Description

[0001] This application is a divisional application of the invention patent application with application number 201680087282.0, application date June 30, 2016, and name "Acrylonitrile Detection Using Biased Electrochemical Sensor". Technical Field

[0002] The present application relates to an acrylonitrile electrochemical sensor, in particular to an acrylonitrile electrochemical sensor using a bias voltage, and an acrylonitrile detection method.

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] not applicable.

[0005] A brief statement of the federally funded research or development

[0006] not applicable.

[0007] References to Microfilm Annexes

[0008] not applicable. Background Art

[0009] When monitoring the presence of various gases, there may be other gases that may react within the sensor, such as carbon monoxide (CO). For example, the working electrode may include a catalyst that may catalyze the reaction of both the target gas and the interfering gas (such as carbon monoxide). Thus, the presence of the interfering gas may create a cross-sensitivity in the sensor, resulting in a false impression that the target gas level is present in the ambient gas at a higher level than is actually present. Due to the dangers presented by the various target gases, the threshold level for triggering an alarm may be relatively low, and the cross-sensitivity created by the presence of the interferent may be high enough to cause the target gas sensor to issue a false alarm. Summary of the invention

[0010] In one embodiment, the electrochemical acrylonitrile sensor includes a housing; an electrolyte disposed in the housing; and a plurality of electrodes in contact with the electrolyte in the housing, wherein the plurality of electrodes include a working electrode and a counter electrode, wherein a potential is applied between the working electrode and the counter electrode.

[0011] In one embodiment, the electrochemical acrylonitrile sensor includes a housing; an electrolyte disposed in the housing; and a plurality of electrodes in contact with the electrolyte in the housing, wherein the plurality of electrodes include: a working electrode and a counter electrode, wherein the working electrode includes a catalytic material, wherein the catalytic material includes gold, wherein the counter electrode includes a catalytic material, wherein the catalytic material includes gold.

[0012] In one embodiment, a method for detecting acrylonitrile includes receiving an ambient gas into a housing of an acrylonitrile sensor, wherein the ambient gas includes acrylonitrile and carbon monoxide, and wherein the acrylonitrile sensor includes a plurality of electrodes in contact with an electrolyte within the housing, wherein the plurality of electrodes include a porous working electrode and a counter electrode; applying a voltage potential between the counter electrode and the working electrode; contacting the ambient gas with the porous working electrode; allowing the ambient gas to diffuse through the porous working electrode to contact the electrolyte; generating a current between the porous working electrode and the counter electrode in response to a reaction between the ambient gas and the electrolyte at a surface area of ​​the working electrode; and determining the concentration of acrylonitrile in the ambient gas based on the current.

[0013] These and other features will become more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the present disclosure, reference is now made to the following brief description taken in conjunction with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0015] Figure 1 A cross-sectional view of an electrochemical sensor according to one embodiment is schematically shown.

[0016] Figure 2 An exploded view of an electrochemical sensor according to one embodiment is shown. DETAILED DESCRIPTION

[0017] First, it should be understood that although exemplary implementations of one or more embodiments are shown below, the disclosed systems and methods can be implemented using any number of technologies (whether currently known or not yet available). The present disclosure should in no way be limited to the exemplary implementations, drawings, and techniques shown below, but can be modified within the scope of the appended claims and the full scope of their equivalents.

[0018] The following brief definitions of terms should apply throughout this application:

[0019] The term "including" is meant to include, but not limited to, and should be interpreted in the manner commonly used in a patent context;

[0020] The phrases "in one embodiment," "according to one embodiment," and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases are not necessarily referring to the same embodiment);

[0021] If the specification describes something as "exemplary" or an "example," it should be understood to mean a non-exclusive example;

[0022] Those skilled in the art will understand that the terms "about" or "approximately" and the like, when used with a number, may refer to a specific number or alternatively to a range around the specific number; and

[0023] If the specification states that a component or feature "may", "can", "could", "should", "will", "preferably", "likely", "usually", "optionally", "for example", "often" or "might" (or other such words) be included or have a property, the particular component or feature is not required to be included or have that property. Such a component or feature may optionally be included in some embodiments, or may be excluded.

[0024] Due to the extreme toxicity of acrylonitrile gas, various countries have enacted regulations to limit personal exposure to the gas. As described herein, various sensors have been developed to detect the presence and concentration of acrylonitrile in the atmosphere. Some methods of detecting acrylonitrile involve using cross-sensitivity in ethylene oxide sensors. However, this method may be difficult to meet requirements in terms of response time and recovery within the sensor. In addition, some sensors may have high cross-sensitivity to carbon monoxide. Due to the high toxicity of acrylonitrile, the sensor alarm level can usually be set to about 2ppm, which means that 1ppm of CO can trigger a false alarm, which in many applications makes the device unusable. Therefore, removing or reducing the cross-sensitivity to CO in acrylonitrile sensors can improve safety.

[0025] There are many ways to enhance the selectivity of electrochemical sensors. First, the choice of materials for the working electrode can affect the overall sensitivity to various chemicals, including the relative sensitivity differences between the target gas and one or more interfering gases. Second, filters can be used to remove interfering gases, thereby reducing the cross-sensitivity to interfering gases. However, filters usually use absorbents or adsorbents with limited capacity, which limits the effective life of the sensor. Third, an intermediate electrolyte system can be used. In this system, the electrolyte composition can be selected so that the electrolyte selectively reacts with the target gas rather than the interfering gas. However, this method can be very complicated, and the electrolyte may also have capacity limitations, resulting in a limited service life of the sensor. Fourth, the potential across the electrodes can be selected to remove or reduce the cross-sensitivity of the sensor. In addition, in some cases, the cross-sensitivity can be reduced by enlarging the capillary pores. However, this may result in a larger potential in the sensor, which may affect multiple parameters in the sensor design, which may not be suitable for sensors with limited sensitivity.

[0026] As a novel way to change the cross sensitivity of electrochemical sensors, electrochemical gas sensors may include gold catalytic materials incorporated into one or more electrodes. In addition, electrochemical sensors may use a potential applied across electrodes. The resulting sensor may have good responsiveness to acrylonitrile gas while having reduced cross sensitivity to CO gas. Generally speaking, the electrochemical sensor disclosed herein includes a gas diffusion working electrode, a counter electrode, and an optional reference electrode. Each electrode is in contact with an aqueous electrolyte.

[0027] Figure 1 is a cross-sectional view of an electrochemical sensor 10. The sensor 10 generally includes a housing 12 that defines a cavity or reservoir 14 designed to hold an electrolyte solution. A working electrode 24 may be placed between the opening 28 and the reservoir 14. A counter electrode 16 and a reference electrode 20 may be positioned within the reservoir. When the gas reacts within the reservoir 14, a current and / or potential may be generated between the electrodes to provide an indication of the gas concentration. The reference electrode 20 may also be positioned within the reservoir 14 to provide a reference for the current and potential detected between the working electrode 24 and the counter electrode 16.

[0028] The housing 12 defines an internal reservoir 14, and one or more openings 28 may be provided in the housing to allow the gas to be detected to enter the gas space 26 through the housing 12. The housing 12 may generally be formed of any material that is substantially inert to the electrolyte and the gas being detected. In one embodiment, the housing 12 may be formed of a polymeric material, a metal, or a ceramic. For example, the housing may be formed of materials including, but not limited to, acrylonitrile butadiene styrene copolymer (ABS), polyoxyxylene (PPO), polystyrene (PS), polypropylene (PP), polyethylene (PE) (e.g., high-density polyethylene (HDPE)), polyphenylene ether (PPE), or any combination or blend thereof.

[0029] One or more openings 28 may be formed through the housing 12 to allow ambient gas to enter the gas space 26 and / or to allow any gas generated within the housing to escape. In one embodiment, the electrochemical sensor 10 may include at least one inlet opening 28 to allow ambient gas to enter the housing 12. The opening 28 may be disposed in the wall of the housing 12, and / or when a cover is present, it may be disposed in the cover. In some embodiments, the opening 28 may include a diffusion barrier to limit the flow of gas (e.g., carbon monoxide, acrylonitrile, etc.) to the working electrode 24. The diffusion barrier may be created by forming the opening 28 as a capillary, and / or a film or membrane may be used to control the mass flow rate through the one or more openings 28.

[0030] In one embodiment, opening 28 can be used as a capillary opening to provide a rate-limited gas exchange between the interior and exterior of housing 12. In one embodiment, the diameter of opening 28 can be between about 200 μm and about 1.5 mm, wherein a conventional drill bit can be used to obtain a larger opening and a laser drill bit can be used to obtain a smaller opening to form opening 28. Depending on the thickness of the cover or housing 12, the length of opening 28 can be between about 0.5 mm and about 5 mm. In some embodiments, there can be two or more openings for inlet gas. When the membrane is used to control the flow of gas into and / or out of the housing, the opening diameter can be larger than the sizes listed above because the thin film can contribute to and / or may be responsible for controlling the flow rate of gas into and out of the housing 12.

[0031] The reservoir includes a counter electrode 16, a reference electrode 20, and a working electrode 24. In some embodiments, an electrolyte may be contained in the reservoir 14, and the counter electrode 16, the reference electrode 20, and the working electrode 24 may be electrically contacted by the electrolyte. In some embodiments, one or more porous separators 18, 22 or other porous structures may be used to keep the electrolyte in contact with the electrode. Separators 18, 22 may include a porous member used as a core, which is used to hold and transport electrolyte between the reservoir and the electrode, while it is electrically insulated to prevent short circuits caused by direct contact between any two electrodes. One or more of the porous separators 18, 22 may extend into the reservoir to provide a path to the electrode for the electrolyte. In one embodiment, separator 18 may be disposed between counter electrode 16 and reference electrode 20, and separator 22 may be disposed between reference electrode 20 and working electrode 24.

[0032] One or more of the separators 18, 22 may include non-woven porous materials (e.g., porous felt members), woven porous materials, porous polymers (e.g., open-cell foams, solid porous plastics, etc.), etc., and are generally chemically inert relative to the electrolyte and the materials forming the electrodes. In one embodiment, the separators 18, 22 may be formed of various materials that are substantially chemically inert to the electrolyte, including, but not limited to, glass (e.g., glass mats), polymers (plastic discs), ceramics, etc.

[0033] The electrolyte can be any conventional aqueous acidic electrolyte, such as sulfuric acid, phosphoric acid or a neutral ion solution, such as a salt solution (e.g., a lithium salt such as lithium chloride, etc.), or any combination thereof. For example, the electrolyte can include sulfuric acid having a molar concentration between about 3M and about 12M. Since sulfuric acid is hygroscopic, the concentration can vary between about 10 to about 70 wt % (1 to 11.5 moles) when the relative humidity (RH) of the environment ranges from about 3 to about 95%. In one embodiment, the electrolyte can include phosphoric acid having a concentration of H3PO4 between about 30 wt % and about 60 wt % in an aqueous solution. For another example, the electrolyte can include a lithium chloride salt having about 30 wt % to about 60 wt % LiCl, the remainder being an aqueous solution.

[0034] The working electrode 24 may be disposed within the housing 12. Gas entering the sensor 10 may contact one side of the working electrode 24 and pass through the working electrode 24 to reach the interface between the working electrode 24 and the electrolyte. The gas may then react to generate a current indicative of the gas concentration. As disclosed herein, the working electrode 24 may include a plurality of layers. The base or substrate layer may include a hydrophobic material or a hydrophobically treated material. The catalytic material may be formed as an electrode on one side of the working electrode 24 and placed in contact with the electrolyte. In one embodiment, the catalytic material in the working electrode may include gold to provide detection of acrylonitrile.

[0035] In one embodiment, the working electrode 24 may include a porous substrate or film as a base layer. For the gas of interest (which may include acrylonitrile), the substrate may be porous. In one embodiment, the substrate may include carbon paper formed by carbon or graphite fiber. In some embodiments, the substrate may be made conductive by adding a conductive material (such as carbon). Using carbon can provide a sufficient degree of conductivity to allow the current generated by the reaction of the gas and the electrolyte at the surface of the working electrode 24 to be detected by the lead coupled to the working electrode 24. Other conductive substrates may also be used, such as carbon felt, porous carbon plates and / or conductive polymers (such as polyacetylene), each of which may be made hydrophobic as described below. Alternatively, conductive leads may be coupled to the catalytic layer to electrically couple the catalytic material to an external circuit, as described in more detail herein. In one embodiment, the thickness of the substrate may be between about 5 mils to about 20 mils in some embodiments.

[0036] The porous substrate may be hydrophobic to prevent the electrolyte from passing through the working electrode 24. The substrate may be formed of a hydrophobic material, or the substrate may be treated with a hydrophobic material. In one embodiment, the substrate may be made hydrophobic by impregnating the substrate with a hydrophobic material such as a fluorinated polymer (e.g., PTFE, etc.). In some embodiments, the substrate or membrane may include GEFC-IES (e.g., a copolymer of perfluorosulfonic acid and PTFE, commercially available from Golden Energy Fuel Cell Co., Ltd.), (Copolymer of polytetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid, available from Dupont TM Commercially available), or pure or nearly pure polytetrafluoroethylene (PTFE). The impregnation method may include using a dipping, coating or rolling process to place a hydrophobic material comprising a solution or slurry on a substrate. Alternatively, a dry composition such as a powder may be applied to the substrate. In some embodiments, an optional sintering process may be used to impregnate the hydrophobic material into the substrate to produce a hydrophobic base layer for the working electrode 24, wherein both sides of the hydrophobic base layer are hydrophobic. The sintering process may bond or fuse the hydrophobic polymer to the carbon of the substrate to firmly bond the hydrophobic material to the substrate.

[0037] The resulting substrate may contain about 30% to about 50% by weight of the hydrophobic polymer. The amount of hydrophobic material added to the substrate may affect the conductivity of the substrate, wherein the conductivity tends to decrease with increasing amounts of the hydrophobic material. The amount of the hydrophobic polymer used with the substrate may depend on the desired degree of hydrophobicity, the porosity to acrylonitrile, and the conductivity of the resulting working electrode.

[0038] The catalytic layer can be formed by mixing the desired catalyst with a binder and depositing the mixture on the substrate material. The binder may include a perfluorinated ion electrolyte solution (e.g., GEFC-IES, etc.), hydrophobic materials (such as PTFE), mixtures thereof, etc. When used as a binder, GEFC-IES, The PTFE and / or PTFE can affect the gas diffusion parameters while loading the electrocatalyst and maximizing the interface between the catalyst, gas and electrolyte where the electrochemical process occurs. Ethylene glycol or other similar chemicals can be used as a diluent to form a catalyst slurry, formulation or catalyst system, which can be printed on a substrate by a printer.

[0039] The catalytic layer may be deposited onto the substrate by, for example, screen printing, filtering in selected areas from a suspension placed on the substrate, by spraying, or any other method suitable for producing a patterned deposition of solid material. The deposition may be the deposition of a single material or the sequential deposition of more than one material in layers, in order to, for example, modify the properties of the electrode material by its thickness, or to add a second layer with increased conductivity above or below the layer that is the main site for the gas reaction. Once deposited, the printed element may be sintered at high temperature to form the electrode.

[0040] In the working electrode 24, the catalytic layer may include gold. The catalyst used may be a pure metal powder, a metal powder combined with carbon, or a metal powder supported on a conductive medium (such as carbon), or a combination of two or more metal powders as a blend or as an alloy. The materials used for each electrode may be the same or different.

[0041] The counter electrode 16 may be disposed within the housing 12. The counter electrode 16 may include a substrate or membrane on which a catalytic material is disposed, such as a PTFE membrane, a GEFC-IES membrane, Membranes, etc. In one embodiment, the catalytic material can be mixed and disposed on the membrane using any suitable process, such as rolling, coating, screen printing, etc. to apply the catalytic material to the membrane, as described in more detail herein. The catalyst layer can then be bonded to the membrane by a sintering process as described herein.

[0042] In one embodiment, the catalytic material for the counter electrode may include one or more metals or metal oxides, such as copper, silver, gold, nickel, palladium, platinum, ruthenium, iridium and / or oxides of these metals. The catalyst loading of the counter electrode 16 may be within any range described herein for the working electrode 24. In one embodiment, the catalyst loading of the counter electrode 16 may be the same or substantially the same as the catalyst loading of the working electrode 24, and the catalyst loading may also be greater or less than the catalyst loading of the working electrode 24.

[0043] In one embodiment, a catalytic material may be added to the working electrode 24, which has a higher catalytic activity for a target gas (such as acrylonitrile) than a single interfering gas or multiple interfering gases (such as carbon monoxide). When the target gas is acrylonitrile and the interfering gas is carbon monoxide, the catalytic material that may be added to the working electrode may include gold (Au). In some embodiments, the selection of catalytic materials may provide desired selectivity. For example, using gold as a catalyst (as opposed to, for example, platinum) may allow certain chemical moieties to react without showing significant reactivity to other chemical moieties. Therefore, the use of gold together with a bias voltage may allow acrylonitrile to be detected with reduced cross sensitivity to various gases (such as carbon monoxide).

[0044] Similarly, the reference electrode 20 may be disposed within the housing 12. The reference electrode 20 may include a substrate or membrane having a catalytic material disposed thereon, such as a PTFE membrane, a GEFC-IES membrane, Membranes, etc. In one embodiment, the catalytic material may be mixed with a hydrophobic material (e.g., PTFE, etc.) and disposed on a PTFE membrane. Any of the methods for forming a working electrode or a counter electrode may also be used to prepare the reference electrode 20. In one embodiment, the catalytic material used with the reference electrode 20 may include one or more metals or metal oxides, such as copper, silver, gold, nickel, palladium, platinum, ruthenium, iridium and / or oxides of these metals. The catalyst loading of the reference electrode 20 may be within any range described herein for the working electrode 24. In one embodiment, the catalyst loading of the reference electrode 20 may be the same or substantially the same as the catalyst loading of the working electrode 24, and the catalyst loading may also be greater than or less than the catalyst loading of the working electrode 24. Although in Figure 1 2 is shown with a reference electrode 20 , but some embodiments of the electrochemical sensor may not include a reference electrode 20 .

[0045] In order to detect the current and / or potential difference across the electrodes generated in response to the presence of acrylonitrile, one or more leads or electrical contacts may be electrically coupled to the working electrode 24, the reference electrode 20, and / or the counter electrode 16. The lead contacting the working electrode 24 may contact either side of the working electrode 24 because the substrate comprises a conductive material. In order to avoid the corrosive effects of the electrolyte, the lead contacting the working electrode may contact the side of the working electrode 24 that is not in contact with the electrolyte. The leads may be similarly electrically coupled to the counter electrode 16 and the reference electrode 20. The leads may be electrically coupled to an external connection pin to provide an electrical connection to an external processing circuit. The external circuit may detect the current and / or potential difference between the electrodes and convert the current into a corresponding acrylonitrile concentration.

[0046] In one embodiment, the sensor 10 may include a bias voltage applied to one or more of the electrodes. For example, a potential may be applied between the counter electrode 16 and the working electrode 24. In other words, the sensor 10 may include a voltage difference between the counter electrode 16 and the working electrode 24 relative to the reference electrode 20. In one embodiment, the potential (or voltage difference) may be about -300 mV.

[0047] In use, the sensor 10 can detect the concentration of acrylonitrile. In use, ambient gas can flow into the sensor 10 through the opening 28, which is used as the air inlet port of the sensor 10. The ambient gas may include acrylonitrile. In some embodiments, interfering gases, such as carbon monoxide, may also be present. The gas may contact the working electrode and pass through the pores of the porous substrate layer to reach the surface of the working electrode 24 treated with the catalyst layer. The electrolyte may contact the surface of the working electrode 24, and the acrylonitrile may react and cause an electrolysis current formed between the working electrode 24 and the counter electrode 16, which corresponds to the concentration of acrylonitrile in the ambient gas. By measuring the current, the concentration of acrylonitrile can be determined using, for example, an external detection circuit.

[0048] During the measurement process, interfering gases such as carbon monoxide may also contact the working electrode 24. Carbon monoxide may react at the surface of the working electrode 24, but the carbon monoxide may not react at the same rate. Carbon monoxide may also experience diffusion resistance within the sensor 10. The choice of catalytic material in the working electrode can limit the reactivity of various interfering gases such as carbon monoxide.

[0049] In one embodiment where additional catalytic material is added to the working electrode 24, the reaction rate of acrylonitrile at the working electrode 24 can be significantly faster than the reaction rate of carbon monoxide at the working electrode 24. By adding a catalytic material that has a higher reactivity toward acrylonitrile than toward carbon monoxide, the relative promotion of the acrylonitrile reaction to the total current is significantly greater than the promotion of the carbon monoxide reaction, which may reduce the cross-sensitivity of the sensor 10 to carbon monoxide to an acceptable level.

[0050] In one embodiment: using the sensor 10 as described herein, the ratio of 1) the sensitivity of the electrochemical sensor to acrylonitrile (e.g., expressed as current per unit of concentration, such as in units of μA / ppm, etc.) to 2) the sensitivity of the electrochemical sensor to carbon monoxide (e.g., in units of μA / ppm, etc.) or cross sensitivity may be greater than about 20, greater than about 40, greater than about 50, greater than about 60, greater than about 80, greater than about 100, or greater than about 125. In one embodiment: 1) the ratio of the sensitivity of the electrochemical sensor to acrylonitrile to the sensitivity of the electrochemical sensor to carbon monoxide may typically be less than about 300 or less than about 200, and the ratio may be in any range from any lower endpoint to any upper endpoint.

[0051] refer to Figure 2, one embodiment of an electrochemical sensor may include a planar arrangement of electrodes. The sensor 210 may include a housing 212 that defines a cavity or reservoir 214 designed to hold an electrolyte solution. A working electrode 224 may be placed between an opening 228 and the reservoir 214. A counter electrode 216 and an optional reference electrode 220 may be positioned in a planar arrangement relative to the working electrode 224, wherein the electrodes may be located in approximately the same plane when the sensor 210 is assembled. When the gas reacts within the reservoir 214, a current and / or potential may be generated between the electrodes to provide an indication of the concentration of the gas. The reference electrode 220 may also be positioned within the sensor 210 to provide a reference for the current and potential detected between the working electrode 224 and the counter electrode 216. In this embodiment, the housing, working electrode 224, counter electrode 216, and optional reference electrode 220 may be positioned relative to the working electrode 224. Figure 1 The same components are the same or similar, but are arranged or constructed differently.

[0052] The housing 212 defines an internal reservoir 214, and one or more openings 228 may be provided in the housing to allow the gas to be detected to enter the housing 212. The housing 212 may generally be formed of any material that is substantially inert to the electrolyte and the gas being detected. In one embodiment, the housing 212 may be formed of a polymeric material, a metal, or a ceramic. For example, the housing may be formed of materials including, but not limited to, acrylonitrile butadiene styrene copolymer (ABS), polyoxyxylene (PPO), polystyrene (PS), polypropylene (PP), polyethylene (PE) (e.g., high-density polyethylene (HDPE)), polyphenylene ether (PPE), or any combination or blend thereof.

[0053] In one embodiment, the electrochemical sensor 210 may include at least one inlet opening 228 to allow ambient gas to enter the housing 212. The opening 228 may be disposed in the wall of the housing 212, and / or when the cover 202 is present, it may be disposed in the cover. In some embodiments, the opening 228 may include a diffusion barrier to restrict the flow of gas (e.g., carbon monoxide, acrylonitrile, etc.) to the working electrode 224. The diffusion barrier may be created by forming the opening 228 as a capillary, and / or a thin film or membrane 204 may be used to control the mass flow rate through the one or more openings 228.

[0054] In some embodiments, the electrolyte may be contained in the reservoir 214, and the counter electrode 216, the reference electrode 220 and the working electrode 224 may be electrically contacted by the electrolyte. In some embodiments, one or more porous separators 218 or other porous structures may be used to keep the electrolyte in contact with the electrode. The separator 218 may include a porous member used as a core, which is used to hold and transport the electrolyte between the reservoir 214 and the electrode, and it is electrically insulating at the same time to prevent a short circuit caused by direct contact between any two electrodes. In one embodiment, the separator 218 may include a continuous material that can be operated to contact each electrode in the electrode. In one embodiment, the separator 218 may be located between the electrode and the reservoir.

[0055] Separator 218 may include non-woven porous materials (e.g., porous felt members), woven porous materials, porous polymers (e.g., open-cell foams, solid porous plastics, etc.), etc., and is generally chemically inert relative to the electrolyte and the materials forming the electrodes. In one embodiment, separator 218 may be formed of various materials that are substantially chemically inert to the electrolyte, including but not limited to glass (e.g., glass mats), polymers (plastic discs), ceramics, etc.

[0056] The electrodes 216, 220, 224 may each contact a pin 230 (or electrical contact), wherein the electrodes may be held in contact with the pin 230 by a pressure pad 232. In one embodiment of the sensor, the pin 230 may include a catalytic material, such as gold. In one embodiment of the sensor 210, a bias voltage may be applied between the working electrode 224 and the counter electrode 216. Although in Figure 2 2 is shown with reference electrode 220 , but some embodiments of the electrochemical sensor may not include reference electrode 220 .

[0057] In a planar configuration, the sensor can be Figure 1 The stacked configuration operates in essentially the same manner as described.

[0058] Various embodiments and methods have been disclosed herein, and the various embodiments may include, but are not limited to:

[0059] In a first embodiment, an electrochemical acrylonitrile sensor includes a housing; an electrolyte disposed within the housing; and a plurality of electrodes in contact with the electrolyte within the housing, wherein the plurality of electrodes include a working electrode and a counter electrode, wherein a potential is applied between the working electrode and the counter electrode.

[0060] A second embodiment may include the sensor of the first embodiment, wherein the potential is greater than about 300 mV.

[0061] A third embodiment may include the sensor of the first or second embodiment, wherein the working electrode includes a catalytic material.

[0062] A fourth embodiment may include the sensor of the third embodiment, wherein the catalytic material includes gold (Au).

[0063] A fifth embodiment may include the sensor of any of the first to fourth embodiments, wherein the counter electrode includes a catalytic material.

[0064] A sixth embodiment may include the sensor of the fifth embodiment, wherein the catalytic material includes gold (Au).

[0065] A seventh embodiment may include the sensor of any of the first to sixth embodiments, wherein the sensor is configured to detect acrylonitrile, and wherein the ratio of 1) the sensitivity of the sensor to acrylonitrile to 2) the sensitivity of the sensor to carbon monoxide is greater than about 50.

[0066] An eighth embodiment may include the sensor of any of the first to seventh embodiments, wherein the electrode comprises a planar arrangement.

[0067] A ninth embodiment may include the sensor of any of the first to seventh embodiments, wherein the electrode comprises a stacked arrangement.

[0068] In a tenth embodiment, the electrochemical acrylonitrile sensor comprises: a shell; an electrolyte disposed in the shell; and a plurality of electrodes in contact with the electrolyte in the shell, wherein the plurality of electrodes comprise: a working electrode and a counter electrode, wherein the working electrode comprises a catalytic material, wherein the catalytic material comprises gold, wherein the counter electrode comprises a catalytic material, wherein the catalytic material comprises gold.

[0069] An eleventh embodiment may include the sensor of the tenth embodiment, wherein the potential is applied between the working electrode and the counter electrode.

[0070] A twelfth embodiment may include the sensor of the eleventh embodiment, wherein the potential is about 300 mV.

[0071] A thirteenth embodiment may include the sensor of any of the tenth to twelfth embodiments, wherein the sensor is configured to detect acrylonitrile, and wherein the ratio of 1) the sensitivity of the sensor to acrylonitrile to 2) the sensitivity of the sensor to carbon monoxide is greater than about 50.

[0072] A fourteenth embodiment may include the sensor of any one of the tenth to thirteenth embodiments, further comprising a reference electrode.

[0073] A fifteenth embodiment may include the sensor of the fourteenth embodiment, further comprising a voltage differential between the working electrode and the counter electrode relative to the reference electrode.

[0074] A sixteenth embodiment may include the sensor of the fifteenth embodiment, wherein the voltage difference is about 300 mV.

[0075] In a seventeenth embodiment, a method for detecting acrylonitrile, the method comprising receiving an ambient gas into a housing of an acrylonitrile sensor, wherein the ambient gas comprises acrylonitrile and carbon monoxide, and wherein the acrylonitrile sensor comprises a plurality of electrodes in contact with an electrolyte within the housing, wherein the plurality of electrodes comprises a porous working electrode and a counter electrode; applying a voltage potential between the counter electrode and the working electrode; contacting the ambient gas with the porous working electrode; allowing the ambient gas to diffuse through the porous working electrode to contact the electrolyte; generating a current between the porous working electrode and the counter electrode in response to a reaction between the ambient gas and the electrolyte at a surface region of the working electrode; and determining the concentration of acrylonitrile in the ambient gas based on the current.

[0076] An eighteenth embodiment may include the method of the seventeenth embodiment, wherein the ratio of 1) the sensitivity of the sensor to acrylonitrile to 2) the sensitivity of the sensor to carbon monoxide is greater than about 20.

[0077] A nineteenth embodiment may include the method of the seventeenth embodiment or the eighteenth embodiment, wherein the working electrode comprises a catalytic gold material.

[0078] A twentieth embodiment may include the method of any one of the seventeenth through nineteenth embodiments, wherein the counter electrode comprises a catalytic gold material.

[0079] Although various embodiments according to the principles disclosed herein have been shown and described above, modifications may be made thereto by those skilled in the art without departing from the essence and teachings of the present disclosure. The embodiments described herein are representative only and are not intended to be limiting. Many variations, combinations and modifications are possible and are within the scope of the present disclosure. Alternative embodiments obtained by merging, integrating and / or omitting the features of one or more embodiments are also within the scope of the present disclosure. Therefore, the scope of protection is not limited by the above description, but by the subsequent claims, which include all equivalents of the subject matter of the claims. Each claim is incorporated into the specification as further disclosure, and the claims are one or more embodiments of one or more of the present invention. In addition, any of the above advantages and features may relate to specific embodiments, but the application of these published claims should not be limited to methods and structures that achieve any or all of the above advantages or have any or all of the above features.

[0080] In addition, the section titles used herein are intended to be consistent with the recommendations of 37 CFR 1.77 or to provide organizational clues. These titles should not limit or characterize the one or more inventions set forth in any claims that may be published from this disclosure. Specifically and by way of example, although the title may refer to the "technical field", the claims should not be limited to describing the so-called field by the language selected under the title. In addition, the description of the technology in the "background technology" should not be interpreted as admitting that a certain technology is the prior art of any one or more inventions in this disclosure. "Invention content" should also not be considered as a limiting characterization of one or more inventions set forth in the published claims. In addition, any reference to the singular "invention" in this disclosure should not be used to prove that there is only one novel point in this disclosure. According to the limitations of multiple claims published from this disclosure, multiple inventions can be set forth, and these claims accordingly define one or more inventions and their equivalents protected by them. In all cases, the scope of these claims should be considered according to the advantages of the claims themselves according to this disclosure, and should not be limited by the titles stated herein.

[0081] It should be understood that the use of broad terms such as "comprising," "including," and "having" provides support for narrower terms such as "consisting of," "consisting essentially of," and "composed essentially of." Use of the terms "optionally," "may," "possibly," and the like with respect to any element of an embodiment means that the element is not required, or, alternatively, the element is required, both alternatives being within the scope of one or more embodiments. Additionally, reference to examples is for illustrative purposes only and is not intended to be exclusive.

[0082] Although several embodiments are provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples should be considered illustrative rather than restrictive, and the present invention is not limited to the details given herein. For example, various elements or components may be combined or integrated into another system, or certain features may be omitted or not implemented.

[0083] In addition, without departing from the scope of the present disclosure, the techniques, systems, subsystems and methods described and shown as discrete or independent in various embodiments may be combined or integrated with other systems, modules, techniques or methods. Other items shown or discussed as being directly coupled or communicating with each other may be indirectly coupled or communicated through some interface, device or intermediate component, whether such coupling or communication is performed electrically, mechanically or otherwise. Other examples of changes, substitutions and alterations may be determined by those skilled in the art and may be made without departing from the spirit and scope disclosed herein.

[0084] This application may include the following technical solutions:

[0085] 1. An electrochemical acrylonitrile sensor (10), comprising:

[0086] Housing (12);

[0087] an electrolyte disposed within the housing (12); and

[0088] A plurality of electrodes (24, 16) are in contact with the electrolyte within the housing (12), wherein the plurality of electrodes (24, 16) include a working electrode (24) and a counter electrode (16), wherein an electric potential is applied between the working electrode (24) and the counter electrode (16).

[0089] 2. The sensor of claim 1 , wherein the potential is greater than about 300 mV.

[0090] 3. A sensor according to Option 1, wherein the working electrode (24) comprises a catalytic material.

[0091] 4. The sensor according to claim 3, wherein the catalytic material comprises gold (Au).

[0092] 5. A sensor according to Option 1, wherein the counter electrode (16) comprises a catalytic material.

[0093] 6. The sensor according to claim 5, wherein the catalytic material comprises gold (Au).

[0094] 7. The sensor of claim 1, wherein the sensor is configured to detect acrylonitrile, and wherein a ratio of 1) the sensitivity of the sensor to acrylonitrile to 2) the sensitivity of the sensor to carbon monoxide is greater than about 50.

[0095] 8. An electrochemical acrylonitrile sensor (10), comprising:

[0096] Housing (12);

[0097] an electrolyte disposed within the housing (12); and

[0098] a plurality of electrodes (24, 16) in contact with the electrolyte within the housing (12), wherein the plurality of electrodes (24, 16) include:

[0099] a working electrode (24), wherein the working electrode (24) comprises a catalytic material, wherein the catalytic material comprises gold (Au); and

[0100] A counter electrode (16), wherein the counter electrode (16) comprises a catalytic material, wherein the catalytic material comprises gold (Au).

[0101] 9. A sensor according to Option 8, wherein a potential is applied between the working electrode (24) and the counter electrode (16).

[0102] 10. The sensor of claim 3, wherein the potential is greater than about 300 mV.

[0103] 11. The sensor of claim 8, wherein the sensor is configured to detect acrylonitrile, and wherein the ratio of 1) the sensitivity of the sensor to acrylonitrile to 2) the sensitivity of the sensor to carbon monoxide is greater than about 50.

[0104] 12. A method for detecting acrylonitrile, the method comprising:

[0105] Receiving an ambient gas into a housing (12) of an acrylonitrile sensor, wherein the ambient gas comprises acrylonitrile and carbon monoxide, and wherein the acrylonitrile sensor comprises a plurality of electrodes (24, 16) in contact with an electrolyte within the housing (12), wherein the plurality of electrodes (24, 16) comprises a porous working electrode (24) and a counter electrode (16);

[0106] applying a voltage potential between the counter electrode (16) and the working electrode (24);

[0107] bringing the ambient gas into contact with the porous working electrode (24);

[0108] allowing the ambient gas to diffuse through the porous working electrode (24) to contact the electrolyte;

[0109] generating an electric current between the porous working electrode (24) and the counter electrode (16) in response to a reaction between the ambient gas and the electrolyte at a surface region of the working electrode (24); and

[0110] A concentration of the acrylonitrile in the ambient gas is determined based on the current.

[0111] 13. The method of claim 12, wherein the ratio of 1) the sensitivity of the sensor to acrylonitrile to 2) the sensitivity of the sensor to carbon monoxide is greater than about 20.

[0112] 14. A sensor according to Option 12, wherein the working electrode (24) comprises a catalytic gold material.

[0113] 15. A sensor according to embodiment 12, wherein the counter electrode (16) comprises a catalytic gold material.

Claims

1. An electrochemical acrylonitrile sensor (10), comprising: Housing (12); an electrolyte, the electrolyte being disposed in the housing (12); a working electrode (24) in contact with the electrolyte within the housing (12) and comprising a catalytic material, wherein the catalytic material comprises gold, wherein the catalytic material is formed as an electrode on at least one side of the working electrode (24) and is placed in contact with the electrolyte, wherein the catalytic material comprises a higher reactivity to acrylonitrile than to carbon monoxide, thereby reducing the cross sensitivity of the sensor (10) to carbon monoxide; and a counter electrode (16), the counter electrode being in contact with the electrolyte in the housing (12), wherein a potential of at least 300 mV is applied between the working electrode (24) and the counter electrode (16), and wherein the sensor (10) is configured to detect acrylonitrile.

2. The sensor (10) of claim 1, wherein the sensor (10) is not configured to detect carbon monoxide.

3. The sensor (10) according to claim 1, wherein the catalyst used in the catalytic material of at least one of the working electrode (24) and the counter electrode (16) comprises one or more of the following: pure metal powder, metal powder combined with carbon, metal powder supported on a conductive medium, and a combination of two or more metal powders.

4. The sensor (10) of claim 1, wherein a ratio of the sensitivity of the sensor (10) to acrylonitrile to the sensitivity of the sensor (10) to carbon monoxide is greater than 20.

5. The sensor (10) of claim 1, wherein a ratio of the sensitivity of the sensor (10) to acrylonitrile to the sensitivity of the sensor (10) to carbon monoxide is greater than 50.

6. The sensor (10) of claim 1, wherein the electrodes (24 and 16) comprise a planar arrangement.

7. A method for detecting acrylonitrile, the method comprising: applying a voltage potential of at least 300 mV between the counter electrode (16) and the working electrode (24); bringing an ambient gas into contact with a porous working electrode (24); allowing the ambient gas to diffuse through the porous working electrode (24) to contact the electrolyte; generating an electric current between the porous working electrode (24) and a counter electrode (16) in response to a reaction between the ambient gas and the electrolyte at a surface region of the working electrode (24); as well as determining a concentration of acrylonitrile in the ambient gas based on the current; wherein the working electrode (24) comprises a catalytic material, wherein the catalytic material comprises gold, and wherein the catalytic material is formed as an electrode on at least one side of the working electrode (24) and is placed in contact with an electrolyte.

8. The method of claim 7, wherein the ratio of the sensitivity of the sensor (10) to acrylonitrile to the sensitivity of the sensor (10) to carbon monoxide is greater than 20.

9. The method of claim 7, wherein the working electrode (24) comprises a catalytic gold material.

10. The method of claim 7, wherein the counter electrode (16) comprises a catalytic gold material.

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